Reviving a Non-Winterized Stored Motorcycle
By Walter F. Kern
Part of a Series, Motorcycle Problems and Solutions
Our Motorcycle Views Forum members often seek solutions to important repair and maintenance problems from the experts on the forum. Many of our best experts are professional motorcycle mechanics or those who have done their own mechanical work and have seasoned practical experience. I've decided to publish a series of motorcycle problems submitted to forums and their solutions. Only the most universal problems will be addressed so most readers will see a problem that may be affecting them. I'll state the problem exactly as posed by a reader and then give a solution based on responses given by our most knowledgable forum members.
Problem from Roadtrip1:
Solution by Hondamototech:
If you find rust in the tank then it all depends on how bad it is. If it's not too bad, you can use an acid liquid called Milkstone remover. It does a pretty good job of getting out the rust. There are a lot of alternatives. The thing I've probably used most is the acid that comes with the Kreem tank lining kit but unless it's REALLY bad I don't use the Kreem as sometime in the future it WILL start coming off and creating all kinds of havoc with the carburetors. If you have a tank that is that bad, unless it's a really rare motorcycle with no parts availability, I usually just find another tank.
The next thing is the battery. If the battery wasn't on a battery tender type charger or some other type of trickle charger, then they go south pretty quickly. But this may be a good thing in the scheme of things and let me tell you why.
If the fuel in the float bowls has turned to varnish, the last thing you want to do is try to start the motorcycle. What happens is the engine tries to suck all that solid varnish material into the idle and main jets and clogs the heck out of them.
The first thing you want to do is drain the tank and make sure there is no rust and trash in there. Check the condition of the fuel in the tank and see if it, in fact, has turned to turpentine or has any solid varnish particles floating around. If it doesn't have varnish or rust in the tank, then flush it out with fresh fuel and put some fresh fuel in it.
Pull the hose off the petcock (fuel valve) and make sure fuel comes out (CB750s have a filter in the petcock) and the filter is not clogged.
While you have the hose off, drain each float bowl on each carburetor by opening the drain valve screw on the lower outer side of each carb's float bowl. If the original drain hoses are still attached, you will have fuel coming out of these four small hoses at the bottom of the bike. If the hoses are gone, then it will drain right on top of the lower end of the motor. Main thing here is you want to inspect this fuel very carefully. If it just smells like bad fuel but doesn't have a bunch of trash in it, that's a good sign. If a lot of brown crud comes out with it, then you will have to pull the carbs and have them cleaned and synchronized by someone who knows how.
If the fuel looks OK, then put the fuel hose back on, turn the fuel valve on, and let some fuel run through the carbs and flush out the float bowls. Then turn the fuel valve off, close all the drain valve screws on the floats and turn the fuel back on. Hopefully, no fuel will run out any of the hoses anymore. If it does, then you have trash in the needle and seat portion of the float and you will have to pull the carbs and clean them.
If all is well so far, then make sure you clean up any fuel that came out from the bike and onto the floor. (You don't want to burn up your new investment.)
Install a new battery, change the oil, pull out the choke and start that bad boy up!
Let it warm up for several minutes and see how it idles. If it idles like total crap and won't "clean out" until you twist the throttle a little, then you have clogged small (idle) jets and you need to pull the carbs and clean them. In some severe instances the mains can be clogged and it won't run at all but if you found no trash when you drained the floats, then you shouldn't have that problem. The main thing here is if you find trash in the fuel coming out of the floats, don't mess around. Just pull the carbs and clean them. DON'T try to start it as you may be sorry later when you try to clear the idle circuit.
If by some chance, you luck out (a year isn't really that long on fuel; I've seen worse), then make sure the tires are good with no dry rot cracks and have proper air pressure.
Make sure the chain and sprockets are in good shape and lubricated. There should be no rust or kinks in the chain and and no worn teeth on the sprockets.
Then go ride!"
If you have a motorcycle repair or maintenance problem that you feel has wide appeal, just post your problem in the Motorcycle Repair Corner of the Motorcycle Views Forum. Only the most universal problems and the best solutions will be considered for inclusion in this series.